1. Field of the Invention
The embodiments described herein generally relate to an apparatus and method for certifying a filter in a containment system without decontaminating the containment system prior to certification. More particularly, embodiments described herein relate to a containment housing isolatable from a sample system and a decontamination system thereby allowing for in-situ testing of a filter disposed in the housing.
2. Description of the Related Art
Numerous facilities handle hazardous and potentially fatal compounds and/or particles. These facilities include, for example, biological safety labs, pharmaceutical manufacturing facilities, biotechnology research labs, and production facilities. The hazardous particulates may include anything that is harmful or fatal to humans including, but not limited to, viruses, bacteria, chemicals, and waste products. Typically a containment system in the facility prevents the hazardous particles from escaping from the facility by filtering the air exiting hazardous areas prior to entering the surrounding environment.
The containment system typically consists of multiple components arranged in series. The components generally include one or more filter housing sections, one or more filters disposed in the one or more filter housing sections, an upstream test section, a downstream test section, and an air tight damper for isolating the containment system from the upstream and downstream ductwork that the containment system is coupled thereto.
The performance of the filters disposed in the containment system is critical to prevent human exposure to the hazardous particles. Therefore, it is necessary to certify the performance (e.g., leak and/or filtration efficiency) of the filters on a regular basis. The certification process ensures that the filters are meeting predefined operations criteria and/or standards. In-situ filter certification is often required for filters handling hazardous particles after the filters installation into the contamination housing. In-situ filter testing is performed by injecting an aerosol challenge upstream of the filter at a known concentration, flowing the aerosol laden air through the filter typically at an operational flow rate, and sampling the air downstream of the filter to determine at least one of a leak (such as pin-hole or edge) or an overall filtration efficiency of the filter based on a predefined filtering performance criteria.
There are two current methods for in-situ certification of a containment system. The first method uses two by-pass ports on the containment housing. A first port is upstream of the filter and a second port is located downstream from the filter. These ports are normally closed. To certify the filters, the containment system is turned off causing the facility to be shut down. The upstream and downstream dampers are closed while the inside of the containment housing is decontaminated by exposure to a decontamination agent. The ports are then opened to allow access to the filter during testing of the filter. The downstream damper and exhaust may be opened to allow the air and aerosol to pass through the filter. Since the containment system has been decontaminated and isolated from the upstream duct work, it is safe to test the filter in the containment system while allowing the air to flow through the exhaust and into the environment.
The second method for in-situ certification of the containment system uses air from the facility. This method requires the upstream and downstream dampers to be closed while the inside of the containment housing is decontaminated. When decontamination is complete the dampers open thereby allowing air from the lab or other work area into the containment system. An aerosol challenge is introduced into the air flowing through the filter to facilitate testing of the filter.
The methods described above are costly and time consuming. The testing process requires the facility and/or the containment system to be shut down during filter testing. The shutdown and decontamination may take several hours and even days in some cases. The loss of time of the facility during a decontamination may cost the facility millions of dollars due to lost research time or production time.
Therefore, there is a need for an improved method and apparatus for testing a filter in a containment system.